In the field of mobile communication systems it is known to use mobile telephones (cellular phones) and other devices using means for wireless communication, hereinafter abbreviated UE for User Equipment. The UE has an omni directional antenna sending out signals in a spherical pattern to a terrestrial network. The terrestrial network is built up from a number of cells managed by a number of base stations connected to ground antennas covering each cell. The ground antennas are normally not omni directional, but restricted to an azimuth angle giving a horizontal sector and an altitude angle giving a vertical sector.
The UEs communicate with that base station having the best communication parameters for the moment. When the communication parameters are altered for the worse, for example when the UE moves away from the base station and migrates to another cell, the UE moves from the weaker base station to a neighbouring base station with better communication parameters.
Cellular networks are sustained by a pattern of adjacent cells of radio coverage. First generation (1G) systems, such as NMT, AMPS, etc. and second generation (2G) system, such as GSM, utilize different frequencies to separate neighboring cells whereas UMTS apply logical coding to achieve cell separation. The reason for using different frequencies and codes respectively is to minimise interference problems for UEs in neighbouring cells.
However, the numbers of frequencies are limited why the cellular pattern has to be repeated in a larger area, in order to use the same frequency a number of times.
When a UE is used onboard an aircraft a problem occurs when the plane is at a distance from the ground because the line of sight from above is so wide that a signal from the UE engages/interferes with a number of cells using the same frequency. For example, if a person onboard an aircraft at an altitude above 3000 m turns on his cellular phone, the omni directional antenna will send in at least the direction of sight and will thus finally engage/interfere with a number of different cells using the same frequency or code. This causes the above mentioned problem with interference for a number of UEs in the terrestrial network and may therefore out voice utilized frequency/timeslot combinations in a large region of the network, also at distances far outside the normal GSM cell radius. Furthermore, it is a waste of recourses to use or block the same frequency in a number of different cells in order to perform the same task. Yet further problems occur if the cells engaged are owned by different network managers. Similar problems occur if a passenger has forgotten to turn off the cellular phone. The cellular phone then communicates to a number of cells in order to announce its position and to roam in on new network operators.
Today there is no method to prevent a mobile from initiating access to any network it has previously been granted access to (on a national/operator level). If the home operator has a roaming agreement with an operator in another country the UE may then be able to interconnect anywhere while within radio coverage of that operator's network.
Even without this approval, all GSM UEs, shall be allowed to make emergency calls in any network while within coverage, why some interaction will take place unless measures are made.
There are also situations when a government, the operator of the network or others, like to prevent a UE to interact with other networks than a dedicated access point or access points.
Therefore, there is a desire for a better communication system that can control communication/traffic to and from a UE in an aircraft, giving no or minimised interference problems in the terrestrial network.